This is the question asked of me by one of my readers. He owns a Nikon D3100 and was confused about his off-camera flash options and how the pop-up works with the system. As I was writing him with what I believed would be a short answer, I soon realized the issue is not as clear-cut as one might think. In fact it can get downright confusing for someone that wants to branch out into off-camera options without any prior experience.
Two Flavors of Off-camera Flash
First, to be clear, this article deals with speedlights (or speedlites depending on your brand) and not with the multitude of studio lights that could also be referred to as off-camera. Considering that, the two different flavors I am speaking of are wireless TTL and radio tripped. Wireless off-camera flash systems utilize a communication link between camera and flash that can be as simple as a radio remote to a sophisticated link that communicates exposure information to the flash for ultimate control. This is known as wireless TTL flash (or iTTL, depending on the manufacturer).
Tethered off-camera flash can achieve similar results but the flash movement is constrained by the limits of the cable. Some cables are very long but typically those that can relay the TTL information are much shorter.
So what’s the big deal with off-camera flash?
If you have take photos using a built-in camera flash, you know that the light is not great. Adding a hotshoe mounted flash can be a little better but still doesn’t provide the best results. You can take steps to improve the quality by using a diffuser or bouncing the light but the options are very limited. By getting the flash off of the camera you can achieve more creative and aesthetically pleasing results that are, in some cases, equal to professional studio lighting. And if you can move the flash off the camera and still maintain exposure control from the camera position, your results will be consistently better with a minimal amount of work from you.
Photo by mescon
Wireless Flash Options
If you are into saving some money, you can create a wireless off-camera setup that is both functional and renders decent results. The one thing that you will probably sacrifice is control. By control, I am referring to the ability to make changes to your flash exposure without leaving your camera. There are a number of radio systems on the market that will allow you to send a trigger signal to your flash directly from the camera through the use of a transmitter and a receiver. There are numerous systems available for wireless flash operation like the Radio Popper, Pocket Wizard, or the budget-minded Cowboy Studio trigger. One of the big advantages to the radio trigger is that the flash does not need to maintain a line-of-site placement with the camera. Most of them also offer extended range of use that is more than adequate for most photographers. For example, many sports shooters who put high-speed strobes into the rafters of an arena will use a Pocket Wizard to trip them due to their power and distance capabilities.
Pocket Wizard used for tripping Nikon Speedlight
Photo by deanwissing
The big disadvantage to the wireless trigger is its inability to transmit exposure information and change flash power output. This means that if an adjustment to the flash is needed, the photographer must move to the flash and dial in the adjustment. Not the end of the World in most cases but it can be a bit of a nuisance at other times. For example, if you have your flash on a light-stand shooting through an umbrella and it is 7 feet in the air, you will need to lower it, make your changes, and then raise it back to the proper position before you resume shooting. This can definitely slow the creative process.
Using one of the wireless TTL options can really change this dynamic to create a smooth, fast workflow. In a wireless TTL system such as the Nikon CLS, the camera communicates via a flash or commander unit to the off-camera flash, sending exposure/meter info and not just a triggering signal. The beauty of this type of system is that exposure changes can be dialed in to the off-camera flash right from the camera position. By being connected to the camera metering system, the flash also changes output as it is moved around the subject. This amount of control is what has made the Nikon, and to some extent, the Canon flash units so popular.
The major downsides to these types of systems are line-of-site, and commander unit requirements. Because these types of flash systems use light to communicate with the camera, they must keep a line-of-site orientation to properly operate. They also have a limited range of use in comparison to radio remotes. Probably the largest downside is the need for a commander unit to communicate between camera and flash.
Commanding the flash
When these types of TTL systems were introduced, there was a need to purchase more than one flash, one for mounting to the camera as a command unit, and one to act as the off-camera flash. The command unit that mounted on the camera hotshoe was/is capable of acting in a duel capacity. It has the option of being a command only unit or it can command and act as an on-camera flash. This is sometime handy for adding a lower powered fill light to be used in conjunction with a main light that is off-camera. Of course if you are using a Nikon SU-800 or Canon ST-ET, you only have the option of controlling the off-camera flashes since these are IR-only units.
Nikon SU-800 Speedlight Commander
A major benefit of using a commander flash is that you can control a large number of flash units from one command unit. Typically this is done by sending signals to different groups and channels. This also allows you to get really creative. You could have one light set up as a main light, one set as a rim light, and another for lighting the background; each with its own exposure values dialed in from the camera-mounted unit. Of course where this all goes South for most folks is in the cost.
Nikon and Canon flashes that are capable of controlling off-camera units can range from $480 for a Nikon SB-900 to $450 for the Canon 580EX-II. Even the SU-800 will run you about $350. That doesn’t count the additional money you will pay out for the off-camera unit. Thankfully you can buy smaller “slave” units for about $150 to $200 less than a command unit.
The new Canon 320-EX Speedlite
The built-in solution
For some camera owners, there is a more economical solution for TTL control of the off-camera flash. Back when Nikon introduced the
D300 D200 DSLR in 2005, there was one feature that no other camera in it’s class had, a pop-up flash that could control the SB-600 or SB-800 flash ( have been told that Pentax also had a wireless built-in system but haven’t been able to find any info on it). It didn’t have quite the versatility as a command flash. Since then, they have included this feature on the D700, and most recently, the D7000 (one of the big reasons that I bought this camera).
Canon also has started including this feature on some of their pop-up flashes models, such as the 60D, 7D, and most recently with the EOS Rebel T3i/600D.
If you don’t own one of these models, you can still wirelessly trigger your flash by putting the flash into “slave” mode. This is a very simple trigger where the flash will look for the light from another flash unit and then fire. It’s not as elegant as the wireless controller and requires line-of-site unlike the radio triggers but it will still work. The only thing to remember is that the light from pop-up flash will be part of the exposure, unlike the models that can be used as controllers.
Hopefully I have been able to shed a little light on the possibilities of off-camera flash options. There is a lot of other information available for learning just how to use them but the best place to start is the Strobist blog. This blog is chock full of information on lighting with small flashes and is supported by a whole community of readers.